Gaui X7 Formula RC Helicopter Review

The Gaui X7 entered the market in 2012. All those years it has proven to be a competitive player in the 700 - class. Last year Dunkan Bossion took second place at the 3D Cup World Edition with this latest addition in the X7 series, the Gaui X7 Formula."

The Gaui X7 Formula contains a series of upgrades over the original X7, including: Formula canopy; Formula rotor-head; upgraded one-way bearing and hub; and spiral tail gears. My kit had the Rotortech main - and tail blades as well as the Gaui Scorpion HKIII-4035-500KV motor included.

The scorpion motors are very good and powerful motors, it is a good combination with the Gaui X7. From what I've heard the ESC for this motor should be In the 120 - 160 amp range. To provide the power we use only the best of the best LiPo batteries on the market nowaday - the Optipower 5,000mAh 50C Ultra packs!

The incorporated BEC of the Talon 120 works perfectly and has a 10A continuous power output with a 20A peak performance. With these specs the BEC is more than capable to provide enough current to the servos. It is very convenient that the BEC comes integrated so we avoid too much cabling.

The 700mm Rotortech main-blades are really good and came perfectly balanced. They have a wide chord thus provide good pop. Plus they look good on the ground as well as in the air.

In response to extreme 3D flight manoeuvres, X7 is equipped with high strength one-way bearing and main gear assembly.

High rigidity X7 braces, adopted two point fixture easy assembly.

GAUI X7 FORMULA RC HELICOPTER BUILD

ABOVE LEFT : All the carbon parts are made of multi-layered, high quality 2.5mm carbon fibre

ABOVE RIGHT : The kit comes with a 10T pinion so you can run up to 2,150rpm

The manual comes from an earlier version of the X7, therefore it contains a few small mistakes such as screw lengths, etc.

The X7 uses three main bearing blocks which increases the vertical frame stiffness.

Installation of the updated parts (formula rotor head and main gear) is explained on the extra included sheets. The drawings are very clear and where needed extra explanation is given, It's clear that this model needs to be built by someone with experience in building model helicopters.

The manual also includes a parts list with part numbers which Is very handy when you need a specific part and you don't know the part number. The manual uses some confusing symbols as to where to put thread lock, etc. I advise to just use common sense and use thread lock on every screw going into a metal part.

After opening the box we find four different part boxes, which contain all the parts needed to assemble the model, These are nicely packed in individual plastic bags to keep them from being scratched and damaged.

The X7 is quite big and feels quite heavy in the air, but the collective and cyclic response is very good and crisp."

The kit also includes some thread-lock, one-way bearing grease, a blade holder, some really nice straps and hook-and-loop tape tor the batteries, straps for securing the electronic and some zip-ties.

GAUI X7 FORMULA RC HELICOPTER CANOPY

1. The powerful Scorpion motor is a good combination for the X7 Formula.2. The rotor-head is based on the classic swash-follower principle.3. The tail box construction is simple with a two-piece tail box.4. The Formula rotor-head also uses an nnovative hub with a bearing supported sleeve.5. The entire transmission assembly has very little drag which improves autorotations.6. The slanted main gear (100T with 1.3 module) is very strong, runs smoothly.

The biggest box contains the canopy, which was nicely wrapped in a plastic bag to prevent damag e during shipping. The canopy is very light, flexible (making it easy to install or remove) with no visible defects in the paint or clear coat (like cracks or impurities). In my opinion the paint scheme is very nice and very visible in the air.

GAUI X7 FORMULA HELICOPTER FRAME ASSEMBLY

The manual starts with the assembly of the upper frame. It wants you to first install all the components on one side of the frame and then install the other side of the frame. The narrow design of the upper frame results in a very stiff and sturdy construction which carries almost all the electronics. The lower frame carries the batteries and landing gear.

The X7 usesthree main bearing blocks which increases the vertical frame stiffness. The motor mount isfixed to the middle main-shaft bearing blocks with two screws. Both features aim to keep the pinion and main gear on a single straight line to prevent the pinion from damaging the main gear, Gaul relies on the strength of the bearing blocks rather than the strength of the screws to transfer the axial forces from the main-shaft to the airframe.

All the carbon parts are made of multi-layered, high quality 2,5mm carbon fibre with no sharp edges. Each part has a very good finish with tight tolerances and no scratches or other surface errors. Everything fits perfectly with no play.

When completed, the frame is built like a tank and will survive most crashes Although every pre-assembled part had Loctite on the screws, I do recommend to check every screw! Gaul advises to use Loctite 263 (red, included) on every screw going into metal. Personally I would advise to tighten the screw and use Loctite 243 (blue). However on the spindle i did use the red Loctite, you don't want those bolts coming loose!

GAUI X7 FORMULA HELICOPTER TRANSMISSION

The slanted main gear (100T with 1.3 module) is very strong, runs very smooth and quiet, The tail is driven by the crown gear on top of the main gear which results In a very compact drive system. The crown gear can be a problem if not done right.

There is a chance the torque tube gear jumps over the crown (similar to a slipping belt) causing excessive wear on both gears. It's very nice to see that for once the main gear isn't warped, reducing vibration and wear on the gear and pinion, The Formula kit already has the upgraded one-way bearing and hub installed so slipping shouldn't be an issue.

I'm sure this main gear can handle any of today's power systems without issue. The entire transmission assembly (including tail drive) has very little drag which improves autorotations.

The kit comes with a 10T pinion so you can run up to 2,150rpm. The pinion is suitable for motor shafts with a diameter of 6mm.

A counter bearing reduces the radial forces on the motor bearings and eliminates motor shaft flex, However, this also means the motor needs to be fitted with an appropriate shaft, (around 51mm long).

A small drawback of this counter bearing isthatsetting the gear mesh isn't easy on this model.

GAUI X7 FORMULA HELICOPTER ELECTRONICS AND SETUP

After mounting the tail and rotor-head to the frame and adjusting the gear mesh of the crown gear, the airframe is complete and it's time to mount the electronics.

The servos are positioned around the main shaft to minimize interactions during swash-plate movement. The geometry is optimised to provide the possibility for a pitch range of more than +/-14° (I went with 12.5°) and still have enough cyclic range. The manual even shows where you can run the wires in order to have a clean look.

Gaui X7 Formula Set-Up Used

Motor : Gaui Scorpion HKIII-4035-500KV

ESC : Castle Creations Talon 120Ah

FBI System : Microbeast

Servos : Align DS615 for Cyclic and DS655 for Tail

BEC : Castle Taion 120

Main-blades : Rotortech 690mm

Tail-blades : Rotortech 105mm

Batteries : 2x Optipower 5000mAh 6S 50C Ultra packs

The kit comes with nice fibreglass reinforced plastic servo horns (Futaba splines). These are very sturdy, however I would advise to use a washer underneath the linkage balls or you could press the ball in the material.

"Once in the air, the X7 helicopter feels stable and predictable"

The manual doesn't give a suggestion on the location of the ball links on the servo horns. However, this position is dependent on the servo-flybarless combination and the preferences of the pilot. I went with the 18mm hole on the stock servo horns which had perfect numbers in the Microbeast. This distance also put the linkages nicely vertical.

ABOVE : Flips and rolls with the X7 Formula feel very balanced.

The suggested lengths of the linkages in the manual was in my case pretty much spot on. I did notice that at zero pitch the swash follower arms were not level. However, there was no binding at full positive pitch and full cyclic so I decided to leave it.

The ESC can be mounted in several locations, since mine issmall enough to mount in the stock position on the front of the helicopter. A larger ESC might not have enough clearance to fit the canopy. I have seen people either modify the canopy or mount the ESC on one side at the frame.

Since the batteries are mounted in the saddle configuration, the weight of the batteries is concentrated around the centre of gravity. This affects the agility of the helicopter. Aileron will be less agile while elevator will be more agile, meaning that flips and rolls will have about the same agility and thus start to feel similar.

However, this does have a drawback: mounting the batteries is rather time consuming. Fortunately Gaui implemented a quick mounting system which greatly simplifies the installation of the batteries.

GAUI X7 FORMULA RC HELICOPTER TAIL

After completing the frame, the manual goes through the assembly of the torque tube-driven tall.

The tail box construction is simple with a two-piece tail box (the tail box and a side plate) that clamps on the boom. Both the boom and tail box are pinned on with a screw to prevent the boom from ejecting and twisting in flight. Just take care to insert the boom completely in the frame and to position the tail before pinning the boom.

"The model flies smoothly, locked-in and does what you tell it to do without any weird tendencies."

The tail transmission uses spiral bevel gears. These run a lot smoother and quieter than the original straight bevel gears. However, the material used in these seems to be a bit weaker compared to the original. They won't strip in flight, but be careful when you hit the tail in long grass, Because of its high tail gear ratio the tail blades are limited to 105mm for rpms below 2,300. Above 2,300 Gaui advises using 95mm tail blades.

The tail pushrod is a single metal pushrod in a carbon tube, This provides the best of both worlds: the security of the metal rod and the stiffness of the carbon tube.

GAUI X7 FORMULA RC HELICOPTER ROTOR-HEAD

Next the manual takes you to the assembly of the rotor-head. The rotorhead is based on the classic swash-follower principle. However, the Formula rotor-head also uses an innovative hub with a bearing supported sleeve in which the spindle is located. Thissleeve transfers all the forces from the collective pitch and the rotation of the rotor head directly to the hub, instead of first going through the dampers.

This means the dampers only need to dampen the see-sawing of the spindle due to the flapping of the rotor-blades. The bearings ensure that the rotation of the spindle, due to the flapping, happens around one point.

This whole construction provides a very precise control system. The swash-plate is play free. The anti-rotation pin has been fitted with bearings so there is no play, friction or wear on the pin and its guide.

The 12mm main-shaft, blade grips, hub, 10mm spindle and links are very strong so they can withstand the abuse of todays hard 3D manoeuvres like overspeeds, etc. The tolerances on the hea a are tight with zero in and out play on the blade grips.

The up and down play of the head assembly is adjusted via shims above and below the main gear, The Formula rotor-head is lower than the original head, bringing the rotor disc closer to the centre of gravity and thus improving the agility of the model.

The ball-links included in the kit are very sturdy and mount firmly on the balls, yet still move freely. The rotor-head linkages are turnbuckles so blade tracking can be tuned perfectly.

GAUI X7 FORMULA RC HELICOPTER TEST FLIGHT

After a final check-up of the helicopter and settings and performing a range-check. It's time for a first flight. Plug fn the batteries and let's fly! While It's spooling up you notice that the drivetrain is very smooth and silent.

Once in the air the X7 feels very stable and predictable. After some simple circuits to get a feeling for the helicopter it's time to switch to Idle Up and start some easy 3D.

The X7 is quite big and feels quite heavy in the air, but the collective and cyclic response is very good and crisp, Tic-tocs keep their attitude quite easily and don't need much collective pitch to change direction. Flips and rolls feel very balanced.

The included Scorpion motor runs very smoothly and provides plenty of power at 2,150rpm. At 2,000rpm the motor wasn't very powerful but was only running at about 60% throttle. The motor also runs a lot cooler at the higher head speed. Moreover the batteries are barely warm after flight.

"The X7 is quite big and feels quite heavy in the air, but the collective and cyclic response is very good and crisp."

As I became more comfortable with the model, I started to push it a bit harder, The piro flips and bunny hops were very locked-in and it was easy to maintain height during hurricanes. Thanks to the smooth drive train, it has a long hang time during an autorotation. Tail control is smooth and I had no problems with tail authority.

The Rotortech blades track amazingly well, have a nice and smooth feeling while still maintaining some pop. They have a good bit of lift and feel snappy during during tic tocs.

GAUI X7 FORMULA RC HELICOPTER :: THE VERDICT

Building the X7 Is easy and straight forward due to the quality of the parts and the construction of the frame. The model flies smoothly, locked-in and does what you tell it to do without any weird tendencies.

Time will tell if there are problems with the durability of the model, but considering the sturdy parts and quality of the hardware I don't expect any problems.

Overall Gaul has delivered a pretty much future proof, high quality kit with excellent flying characteristics.

100% Secure Payments

Redback Aviation Helicopter Store is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com, Endless.com, MYHABIT.com, SmallParts.com, or AmazonWireless.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.